﻿using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

    /// <summary>
    /// 对称加密算法类
    /// </summary>
    public class SymmetricMethod : IDisposable
    {

        private SymmetricAlgorithm mobjCryptoService;
        private string Key;

        /// <summary>
        /// 对称加密类的构造函数
        /// </summary>
        public SymmetricMethod()
        {
            mobjCryptoService = new RijndaelManaged();

            // 设置密钥
            Key = "msoemmicromarketing";
        }

        public SymmetricAlgorithm IsDisposed
        {
            get { return mobjCryptoService; }
            set { mobjCryptoService = value; }
        }

        ~SymmetricMethod()
        {
            InternalDispose(false);
        }

        public void Dispose()
        {
            InternalDispose(true);
        }

        protected void InternalDispose(bool disposing)
        {
            if (disposing)
            {
                GC.SuppressFinalize(this);
                //mobjCryptoService.
               // _managedThing.Dispose();
            }
            //_unmanagedThing.Dispose();

        }


        /// <summary>
        /// 获得密钥
        /// </summary>
        /// <returns>密钥</returns>
        private byte[] GetLegalKey()
        {
            string sTemp = Key;
            mobjCryptoService.GenerateKey();
            byte[] bytTemp = mobjCryptoService.Key;
            int KeyLength = bytTemp.Length;
            if (sTemp.Length > KeyLength)
                sTemp = sTemp.Substring(0, KeyLength);
            else if (sTemp.Length < KeyLength)
                sTemp = sTemp.PadRight(KeyLength, ' ');

            return ASCIIEncoding.ASCII.GetBytes(sTemp);

        }

        /// <summary>
        /// 获得初始向量IV
        /// </summary>
        /// <returns>初试向量IV</returns>
        private byte[] GetLegalIV()
        {
            // 失量
            string sTemp = "Doyoulikemicromarketing?";

            mobjCryptoService.GenerateIV();
            byte[] bytTemp = mobjCryptoService.IV;
            int IVLength = bytTemp.Length;
            if (sTemp.Length > IVLength)
                sTemp = sTemp.Substring(0, IVLength);
            else if (sTemp.Length < IVLength)
                sTemp = sTemp.PadRight(IVLength, ' ');

            return ASCIIEncoding.ASCII.GetBytes(sTemp);

        }

        /// <summary>
        /// 加密方法
        /// </summary>
        /// <param name="Source">待加密的串</param>
        /// <returns>经过加密的串</returns>
        public string Encrypto(string Source)
        {
            byte[] bytIn = UTF8Encoding.UTF8.GetBytes(Source);
            MemoryStream ms = new MemoryStream();
            mobjCryptoService.Key = GetLegalKey();
            mobjCryptoService.IV = GetLegalIV();
            ICryptoTransform encrypto = mobjCryptoService.CreateEncryptor();
            CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Write);
            cs.Write(bytIn, 0, bytIn.Length);
            cs.FlushFinalBlock();
            ms.Close();
            byte[] bytOut = ms.ToArray();

            return Convert.ToBase64String(bytOut);

        }

        /// <summary>
        /// 解密方法
        /// </summary>
        /// <param name="Source">待解密的串</param>
        /// <returns>经过解密的串</returns>
        public string Decrypto(string Source)
        {
            byte[] bytIn = Convert.FromBase64String(Source);
            MemoryStream ms = new MemoryStream(bytIn, 0, bytIn.Length);
            mobjCryptoService.Key = GetLegalKey();
            mobjCryptoService.IV = GetLegalIV();
            ICryptoTransform encrypto = mobjCryptoService.CreateDecryptor();
            CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);
            StreamReader sr = new StreamReader(cs);

            return sr.ReadToEnd();

        }
    }


